Albert Barnes Commentary Psalms 37:13

"The Lord will laugh at him; For he seeth that his day is coming." — Psalms 37:13 (ASV)

The Lord shall laugh at him — See the notes at Psalms 2:4. That is, He will regard all his attempts as vain — as not worthy of serious thought or care. The language is what we use when there is no fear or apprehension felt. It is not that God is unfeeling, or that He is disposed to deride man, but that He regards all such efforts as vain, and as not demanding notice on account of anything to be feared from them.

For He sees that his day is coming — The day of his destruction or overthrow. He sees that the wicked man cannot be ultimately successful, but that destruction is coming upon him. There is nothing ultimately to be feared from his designs, for his overthrow is certain.